Physiological mechanism that maintains normal ICP
WHAT IS ICP: the hydrostatic force measured in the brain CSF compartment, under NORMAL condition the balance among the 3 remain constant
NORMAL ICP: 5 - 15 mmHg (anything above 20 mmHg is considered abnormal and must be treated)
MEASUREMENT OF ICP:
- Vent
Anything that increases ICP or can influence it include:
Arterial pressure
Venous pressure
Intraabdominal pressure
- bearing down
- valsalva maneuver
- constipation
(make sure patient is on a stool softener to avoid these)
Intrathoracic pressure
- coughing
- sneezing
Posture
- HOB too high or too low
(keep the
Monroe-Kellie Doctrine
The 3 components must remain at a constant volume within the closed skull structure. if any of these volume increases, a volume from another component decreases.
Ex: if a patient gets into a car accident and hits their head, now has a brain contusion, som
Review on maintaining ICP
Blood
- blood vessels constrict = less blood flow
- blood vessels dilate = engorged blood flow
- collapse of veins --> large ventricles compressing --> high CSF
- Any increase in production of ICP or absorption of ICP will push into the brain or constrict
Increased ICP (CM)
EARLY SIGN:
- ANY change in LOC
- unequal pupil size
- mild-severe headache, often rapid onset
- projectile vomiting (unexpected vomiting not proceeded by nausea)
- seizure
- change in sleep pattern
- change in sensory perception, blurred vision
LATE SIGN
Cerebral Blood Flow (CBF)
- CBF is the amount of blood in mL passing through 100g of brain tissue in one minute. Normal is 50 mL/min.
- the brain uses 20% of body's oxygen and 25% of its glucose
- the brain can auto regulate to ensure its getting enough oxygen and glucose = auto r
Management of ICP
- Maintain adequate oxygenation PaO2 at greater than or equal to 100 mmHg
- Maintain PaCO2 30-35 mmHg
- Elevate the HOB 30 degrees
- Mannitol
- Lasix to decrease the production of CSF
- hypertonic solutions
- corticosteroids (dexamethasone/decadron) used
Cerebral perfusion pressure
CEREBRAL PERFUSION PRESSURE (CPP) is the pressure needed to ensure blood flow to the brain. (It is critical to maintain MAP if you have a high ICP)
- Normal CPP = 70-100 mmHg
- CPP < 50 mmHg = ischemia and neuronal death occur
- CPP < 30 mmHg = necrosis a
Neuro exam: Glasgow Coma Scale
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Head injuries (fracture, concussion, contusion):
Mechanism of injury
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Cerebral Edema
- Extra extravascular fluid in the brain
- Three types:
o Vasogenic cerebral edema
� Most common
� Shift of fluid from intravascular to extravascular
� Causes: brain tumor, abscesses, ingestion of toxins
o Cytotoxiccerebral edema
� Occurs as a result a fl
Head injuries (fracture, concussion, contusion): CM
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Assessment factors for clients experiencing head injury
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Nursing interventions r/t to head injury
Collab care
DX
Pharmacological therapies